I have a 99 DeVille and when i start the car up it idles about 1000rpm at first then when u put it in drive the car drives normal but when you come to a stop you notice that it still revs high. Then when I came home and started parking it got worst (when switching to reverse causing the tranny to bang into the gear really hard) Then when i put it in park it wasbetween 3000-3500rpms. I really need help on this one thanks.

 

hey i use to work at a small car lot and we got a 97 deville that was doing that same thing you describe, we eneded up at the end of all the testing we did that it had a bad tps sensor a throttle postion sensor, the sensor is tell you computer that the throttle is open when it is not try unpluging the sensor and start car if it continutes to go up turn off right away, and take it to the dealer, but we replace the tps sensor and it worked for us, the sensor is right in front connected the the throttle body by two hex head bolts, be sure to mark the angle that the tps came off because the angle can be adjusted for higher or lower rpms so mark where the old one is

let us know wat happens

 

yea i agree. i was thinking tps or iacv. thanks will look into it and let you know the outcome